Ceramic 'magic spheres' make optical computers actually possible

After a pleasant half-century of rapid improvements in electron-based computers, it's well known that the push for quicker and quicker processors (or co-processors) is hitting a wall.

There are several ways computer scientists think we might push past it -- including computers able to use quantum states instead of ones and zeros, and organic computers more closely able to mimic the human brain.

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Optical computers, which would use photons instead of electrons are also mooted as a potentially revolutionary new technique. But despite years of promising research, even the basic foundations of the idea remain shaky at best.

New research from a team of Russian, Spanish and French scientists might just have secured that ground -- or given future researchers a place to stand. Led by Professor Michael Tribelsky from the MV Lomonosov Moscow State University,the research published in Scientific Reports claims to have demonstrated an experimental sphere capable of redirecting scattered light with enough control to potentially form the basis of a computer processor.

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Controlling light on a very small scale with enough precision to make optical computing possible has been a long-standing problem. The issue is that the wavelength of visible light (0.5 micrometers) is too large to be usable in modern electronics. Working with light below that scale is incredibly difficult and fundamentally different to the type of optics we are used to dealing with in everything from the human eye to cameras.

Various attempts to find practical methods for controlling subwavelength light have are being explored -- including plasmonics, which looks at how the oscillations of electron gas in metals can be controlled to produce a clear signal -- but no solution has emerged. The problem is that the electric conductors like copper or platinum used in plasmonics still exhibit resistance, and that dampens the oscillation by which digital signals could be created and used as the lifeblood of a computer.

Lomonosov Moscow State University

Tribelsky's new research, which builds on a theoretical paper he first published in 1984, instead looks at finding new ways to produce a similar signals. These dielectric materials would be able to exhibit a clearly polarised resonance -- the goal of plasmonics -- without the associated 'dampening' caused by electrical resistance in metals. These materials, which critically have a high refraction index, are in theory able to demonstrate similar effects without the damping effect -- and could be used as the core components of tiny optical computing circuits.

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In the experiment, Tribelsky's colleagues worked with ceramic spheres about 2cm in diameter, and showed they could redirect electromagnetic radiation (in this case that similar to a microwave oven) very accurately -- and could tune that scattering by changing the type of waves fired at it. The details of how the sphere works are complex, but the key is that its fundamental physical properties allowed the team to redirect "incident radiation" -- an 'in' signal, in the desired way -- and that is the basic requirement of a computer. "Suffice to say that the researchers managed to separate the desired signal from background whose amplitude sometimes was 3000 times larger than that of the signal," Tribelsky said in a press statement.

Obviously a sphere of 2cm is much too big to be used in computers. But the key to the research, Tribelsky says, is that objects on a much smaller scale will work in exactly the same way if their refractive index is the same -- and the technology to make these much smaller spheres already exists. The nanospheres able to be used in an optical circuit would not require "exotic" materials and would be applicable in every form of computing and recording, and are much simpler than other alternatives.

That doesn't mean optical processors will be in your next iPhone. But it does at least appear to show that a physical optical computer is possible -- and since Moore's Law is rapidly nearing breaking point, that can only be a good thing.